You are competing with the team you are playing that week in each category. In a 5x5 league you would get a point for every stat category you fared better than your opponent. If you win 6 categories and your opponent wins 4 the week ending score would be 6-4. Your record is the total of combined wins over the course of a seaosn and combined loses for each category. For instance if you won every category the next week (10-0) your record would now be 16-4.

to answer your question yes it is essentially weekly roto matchups. reds answer is basically correct, but also keep this in mind. you can beat your opponent every week of the season and may not be in 1st place. because you are essentially playing against every team in the league even though you are matched up against one opponent for the week. getting the most cats against your opponent in a given week doesn't mean you get the most cats in the league for the week. in other words your position is determined by the number of cats won not you win loss record.